The film stars the terrific Jaeden Lieberher (“St. Vincent,” “Midnight Special”) as Henry Carpenter, an 11-year-old with the mind of a middle-aged man.

Henry is, to put it mildly, a genius. He makes amazing Rube Goldberg-ish kinetic constructions in the spectacular forest treehouse he’s fashioned from found parts. He’s a day trader who has managed to wrack up $1 million in cash and securities (how an 11-year-old can get away with this is never explained). Wherever he goes Henry is the smartest guy in the room.

Which is good for his single mom Susan (Naomi Watts) and his tremulous little brother Peter (Jacob Tremblay of “Room”). Susan is a bit of a flake, addicted to violent video games and boozy binges with her bestie (Sarah Silverman). She works as a waitress and drives a beat-up car even though Henry (being the responsible grownup) keeps reminding her that there’s plenty of money.

Jaeden Lieberer, Jacob Tremblay, Naomi Watts

Living next door is the local police bigwig Glenn (Dean Norris), a widower whose stepdaughter Christina (Maddie Ziegler) is Henry’s classmate. She’s a sad girl who often hangs at Henry’s house where Susan showers her with hugs. Only Henry suspects that Glenn is sexually abusing Christina, although his attempts to get the authorities interested have been stymied (turns out the main abuse investigator is Glenn’s brother).

An hour into “The Book of Henry” something really traumatic happens and Henry vanishes from the film — physically, anyway.

But he leaves behind a hand-written book filled with illustrations and a series of tape recordings. He has an elaborate step-by-step plan is to kill the abusive Glenn…and have his mother do it.

Like I said, creepy.

Here’s the thing: “The Book of Henry” has been so well acted that the players are almost able to sell the crock of improbable b.s. that is Gregg Hurwitz’s screenplay. You may find yourself rooting for them even while the film leaves you cold.

Director Trevorrow, who scored indie creds with his low-budget time-travel film “Safety Not Guaranteed,” has moved on to big-budget epics (“Jurassic World” and the next “Star Wars” entry). “…Henry” may be his last chance to make a “little” picture.